S27E135: Miranda's Oceanic Mystery, Mars' Green Spotted Rocks, and the 2035 Martian Walk Target

[00:00:00] This is SpaceTime Series 27 Episode 135, for broadcast on the 8th of November 2024.

[00:00:07] Coming up on SpaceTime, could Uranus' moon Miranda have a subsurface ocean?

[00:00:12] NASA discovers weird red rocks with green spots on Mars.

[00:00:17] And it looks like the first humans could be walking on the Martian surface as early as 2035.

[00:00:24] That's just over a decade away.

[00:00:25] All that and more coming up on SpaceTime.

[00:00:30] Welcome to SpaceTime with Stuart Gary.

[00:00:34] A new study suggests that Uranus' moon Miranda could be harbouring a liquid water ocean beneath its strange jigsaw-like surface.

[00:00:58] If true, the findings reported in the Planetary Science Journal would challenge many assumptions about the moon's history and composition

[00:01:04] and could place it in the same company as the few selected worlds in our solar system with potentially life-sustaining environments.

[00:01:12] One of the study's authors, Tom Nordheim from the Johns Hopkins Applied Physics Laboratory, says finding evidence of an ocean inside a small object like Miranda is incredibly surprising.

[00:01:22] It helps build on the story that some of these tiny moons at Uranus may in reality be really interesting, that there may be several ocean worlds around what is one of the most distant planets in our solar system.

[00:01:34] And that's both exciting and bizarre.

[00:01:37] Among the moons in our solar system, Miranda stands out.

[00:01:42] The few images Voyager 2 captured of Miranda back in 1986 only show its southern hemisphere.

[00:01:48] And that's a Franken-star-like hodgepodge of grooved terrain, quartered off by rough scarps and crated areas, like squares on a quilt.

[00:01:56] Originally, scientists thought this could be the result of a huge cosmic collision, the moon being totally shattered and then gravitationally coming back together in a hodgepodge fashion.

[00:02:06] Nowadays, most astronomers suspect the bizarre structures are actually the result of gravitational tidal forces and heating within the moon.

[00:02:14] But to find out what's actually going on there, astronomers set out to explain Miranda's enigmatic geology by reverse engineering the surface features,

[00:02:22] working backwards to uncover what the moon's interior structure must have been like in order to shape the moon's geology in response to gravitational tidal forces.

[00:02:30] After first mapping the various surface features, like cracks, ridges and Miranda's unique trapezoidal coronae,

[00:02:37] the authors developed a computational model to test several possible structures for the moon's interior,

[00:02:42] eventually matching predicted stress patterns to the actual surface geology.

[00:02:47] The setup that produced the best match between predicted stress patterns and observed surface features

[00:02:52] required the existence of a vast ocean beneath Miranda's icy surface some 100 to 500 million years ago.

[00:02:59] That subsurface ocean would have been at least 100 kilometers deep,

[00:03:03] and it would have been hidden beneath an icy crust no more than 30 kilometers thick.

[00:03:08] Now, given that Miranda only has a radius of 235 kilometers,

[00:03:11] it means the ocean would have filled almost half the moon's volume.

[00:03:15] Gravitational tidal forces between Uranus, Miranda and other nearby moons would have been key to creating that liquid ocean.

[00:03:22] And these regular gravitational tugs could have further been amplified by orbital resonances,

[00:03:28] a configuration during which each moon's period around the planet is an exact integer of another moon's periods.

[00:03:34] For example, Jupiter's moons Io and Europa have a 2-1 resonance.

[00:03:38] For every two orbits Io makes around Jupiter, Europa makes exactly one,

[00:03:43] leading to tidal forces that are known to sustain a liquid water ocean beneath Europa's surface.

[00:03:48] These orbital configurations and the resulting gravitational tidal forces deform the moons like rubber balls,

[00:03:55] leading to friction and heat that keeps the interiors warm,

[00:03:58] keeping the water liquid instead of turning it to solid ice.

[00:04:02] And this also creates stresses that cracks the surface,

[00:04:05] resulting in a rich tapestry of geological features.

[00:04:09] Numerical simulations suggest that Miranda and its neighboring moons likely also had similar resonances in the past,

[00:04:15] offering a potential mechanism that could have warmed Miranda's interior in order to produce and maintain a subsurface ocean.

[00:04:22] Now at some point these moons orbital ballet desynchronized,

[00:04:26] slowing the heating process so that the moons insides began cooling and solidifying.

[00:04:31] But the authors don't think that Miranda's interior has fully frozen yet.

[00:04:37] Nordheim says that had the ocean fully frozen,

[00:04:39] it would have expanded and caused certain telltale cracks on the surface which aren't there.

[00:04:44] So this suggests that Miranda is still cooling,

[00:04:47] and so it may still have a liquid water ocean beneath its surface even now.

[00:04:51] But Miranda's modern day ocean would probably be fairly thin.

[00:04:56] Still when you think about it, Miranda wasn't predicted to have an ocean at all.

[00:05:00] With its small size and old age, scientists thought it would most likely simply be a solid frozen ball of ice.

[00:05:06] Any leftover heat from its formation was assumed to have dissipated long ago.

[00:05:11] But as we all know, predictions of ice moons can be really wrong, as evidenced by Saturn's moon Enceladus.

[00:05:17] See, before NASA's Cassini mission to the Saturnian system in 2004,

[00:05:22] many scientists thought Enceladus was simply a frozen ball of ice and rock.

[00:05:26] But once Cassini got there, we discovered it's actually harbouring a global subsurface liquid water ocean,

[00:05:32] and it even has active geological processes taking place.

[00:05:36] In fact, it's constantly shooting water vapour and ice out of its southern hemisphere tiger-striped geysers.

[00:05:42] And these are now a prime target of research for life beyond Earth.

[00:05:46] And that raises the tantalising question of whether Miranda could be a similar case.

[00:05:51] It's comparable in size and composition to Enceladus, and according to a 2023 study led by Johns Hopkins University's Ian Cohen,

[00:05:59] it may also be actively releasing material into space.

[00:06:02] So if it has or ever had an ocean, it should be a future target for studying habitability in life.

[00:06:09] This is space-time.

[00:06:11] Still to come, NASA's Mars Perseverance rover discovers strange red rocks with green spots on the red planet,

[00:06:18] and it looks like the first humans could be walking on the red planet in just over a decade from now.

[00:06:23] All that and more still to come on Space Time.

[00:06:42] NASA's Mars Perseverance rover has discovered strange red rocks with green spots

[00:06:47] as it continues its journey up towards the rim of the red planet's Jezero crater.

[00:06:51] Just 20 sols, or Martian days after discovering and sampling the unusual lipid spots of Bright Angel,

[00:06:58] the six-wheeled car-sized robotic laboratory drove south across Nevetra valleys to a location named Serpentine Rapids.

[00:07:06] There, scientists discovered a strange new geologic puzzle of enigmatic and unique red and green rocks.

[00:07:12] Perseverance then used its braiding tool to create an abrasion patch in the rock outcrop,

[00:07:17] which they've named Wallace Butte.

[00:07:18] The five-centimeter diameter abrasion patch revealed a striking array of white, black and green colours within the rock.

[00:07:26] One of the biggest surprises for mission managers was the presence of the drab green-coloured spots within the abrasion patch.

[00:07:32] They're composed of dark-toned cores with fuzzy light green rims.

[00:07:37] On Earth, red rocks, sometimes called red beds, generally get their colour from oxidised iron,

[00:07:42] which is the same form of iron that makes your blood turn red or the rusty red colour of metal left outside.

[00:07:49] Green spots, like those observed in the Wallace Butte abrasion, are common in ancient red beds on Earth,

[00:07:54] and they form when liquid water percolates through sediments before it hardens into rock,

[00:07:59] kicking off a chemical reaction that transforms oxidised iron to its reduced form, resulting in a greenish hue.

[00:08:05] Now here on Earth, microbes are sometimes involved in this iron reduction reaction.

[00:08:10] However, green spots can also result from decaying organic matter, which creates localised reducing conditions.

[00:08:16] But before you get too excited, interactions between sulphur and iron can also create iron-reducing conditions

[00:08:23] without the involvement of any microbial life.

[00:08:25] Now unfortunately, at this location there simply wasn't enough room to safely place the rover's robotic arm,

[00:08:31] containing the Sherlock and Pixel instruments, directly over one of the green spots within the abrasion patch.

[00:08:37] So, sadly, their exact composition remains a mystery.

[00:08:41] This is space-time.

[00:08:42] Still to come, the first humans could be walking on Mars as soon as 2035.

[00:08:48] And later in the science report, a new study shows that children exposed to cannabis in the womb

[00:08:54] are more likely to have behavioural issues.

[00:08:56] All that and more still to come on Space Time.

[00:09:14] NASA says it could send humans to the Moon potentially as early as 2035.

[00:09:20] However, it won't be a fast journey.

[00:09:22] A 402 million kilometre round trip would take up to 14 months in travel time,

[00:09:27] with the crew staying on the red planet for up to 500 days before returning to Earth.

[00:09:32] However, the exact length of the Martian surface stay would depend on the orbital alignment of the Earth and Mars at the time.

[00:09:38] A manned journey to the red planet would be the culmination of NASA's Artemis program,

[00:09:44] which will see humans back in orbit around the Moon aboard the Artemis 2 mission next year

[00:09:49] and a return to the lunar surface aboard Artemis 3 in late 2026.

[00:09:54] To send people to the Moon, and eventually onto Mars,

[00:09:57] NASA has developed a new heavy lift launch vehicle called the Space Launch System or SLS,

[00:10:01] and a new long-range spacecraft called Orion.

[00:10:04] The SLS, together with an unmanned Orion capsule,

[00:10:08] successfully launched on November 16, 2022 on the Artemis 1 mission.

[00:10:12] That undertook multiple orbits of the Moon before returning safely to the Earth.

[00:10:17] Another key part of the project is the Lunar Gateway Space Station,

[00:10:21] which will be placed into cislunar orbit sometime around 2027.

[00:10:24] It will act as a base camp for crews, supplies and scientific equipment

[00:10:29] being transferred from the Earth to the lunar surface.

[00:10:32] And Gateway will also act as the prototype for the manned spacecraft,

[00:10:36] providing crew accommodation during the six- to seven-month long interplanetary journey.

[00:10:41] Gateway is a joint project involving NASA, the European Space Agency,

[00:10:46] and the Japanese Aerospace Exploration Agency.

[00:10:49] Artemis astronauts will live and work on the Moon for months at a time

[00:10:52] in order to prepare for living and working on the Red Planet.

[00:10:56] ESA's Head of Legal Services, Marco Ferenczi, says

[00:10:59] Gateway will provide a key component of the Artemis plan to return to the Moon

[00:11:03] and maintain what will be a permanent human presence there.

[00:11:06] On October 2020 this year, ESA has signed an historical agreement

[00:11:11] in the form of a memorandum of understanding with NASA

[00:11:14] concerning cooperation on the civil lunar gateway.

[00:11:17] The lunar gateway is an essential component of the sustainable conduct

[00:11:21] of lunar operations and will also play a major role in NASA's Artemis Exploration Program.

[00:11:28] It is a genuine partnership with NASA, committing ESA to a civil human outpost in lunar vicinity.

[00:11:35] Every launch of astronaut to the Moon on board the new Orion

[00:11:38] will rely on the European Space Module for power, propulsion, oxygen and water.

[00:11:44] Europe will provide crew accommodation, telecommunication refueling and amazing views of the Moon.

[00:11:51] And what is more, European astronauts will fly to the Gateway

[00:11:54] and to live and work in deep space for the first time.

[00:11:58] Activities beyond the scope of the Gateway, such as future lunar surface activities,

[00:12:03] are not addressed in this MOU and will be subject to future cooperation agreements

[00:12:08] with international partners, with the expectation to complete a multilateral scheme

[00:12:12] as for International Space Station, before a human mission reaches the lunar surface.

[00:12:18] So more international agreements are to come.

[00:12:22] As part of the Artemis Exploration Program, NASA has also introduced the Artemis Accords

[00:12:28] as an initiative to establish a common set of principles applicable to the Artemis Lunar Exploration Program.

[00:12:35] As opposed to the Gateway and MOU, which are among exploration and ISS partners,

[00:12:41] these accords do not constitute binding international agreements

[00:12:45] but rather political commitments to a practical set of principles, guidelines and best practices.

[00:12:52] That's ESA's Head of Legal Services, Marco Ferenczi.

[00:12:55] And this is Space Time.

[00:13:14] And time now to take another brief look at some of the other stories making news in science this week

[00:13:18] with a science report.

[00:13:19] A new study has found that children who are exposed to cannabis in the womb

[00:13:24] are more likely to have behavioural issues as they grow.

[00:13:27] The findings, reported in the Journal of the American Medical Association,

[00:13:31] assess the capability and behaviour of 255-year-olds

[00:13:34] whose mothers had participated in pregnancy research.

[00:13:37] According to urine tests and surveys,

[00:13:40] 70 of those kids have been exposed to cannabis while in the womb.

[00:13:44] The authors found that children who had pre-birth cannabis exposure

[00:13:48] consistently scored lower for self-control and attention,

[00:13:51] showed poorer task-based planning and ability

[00:13:54] and showed more aggression compared to those who had not been exposed to cannabis before birth.

[00:14:00] A new study has shown that ancient human DNA indicates two genetically distinct populations of people

[00:14:06] arose north and south of the Caucasus mountains on the border between Europe and Asia

[00:14:11] around the 7th millennium BCE.

[00:14:13] The findings, reported in the journal Nature,

[00:14:16] showed that the northern population remained mainly as hunter-gatherers,

[00:14:19] but the southern population went on to become some of the war's first pastoralists

[00:14:23] around the 4th millennium BCE.

[00:14:26] Exactly what spurred this lifestyle change remains a mystery,

[00:14:30] but farmers from Anatolia may have introduced the farming practices to the locals.

[00:14:34] To reach their conclusions,

[00:14:36] the authors looked at DNA from 131 people from across the Caucasus region

[00:14:40] between the Mesolithic, that's the 7th millennium BCE,

[00:14:43] and the Late Bronze Age, the 2nd millennium BCE.

[00:14:46] They noted that the populations north and south of the Caucasus mountains

[00:14:50] became genetically distinct during the Mesolithic,

[00:14:53] suggesting they were isolated from each other by the mountains.

[00:14:56] The northern population had hunter-gatherer DNA linked to people from the east,

[00:15:01] while the southern population had a mix of Corsican hunter-gatherer DNA

[00:15:04] and DNA from people from Anatolia.

[00:15:08] A new study by scientists at the University of Pennsylvania and Cambridge University

[00:15:13] has found that Airbnbs are often associated with more crime.

[00:15:18] The findings reported in the journal Criminology looked around the London area,

[00:15:23] showing an increase in robbery, burglary, theft and violence associated with Airbnbs.

[00:15:28] Since its founding in 2008, the short-term home stay platform Airbnbs

[00:15:33] has expanded to 100,000 cities in more than 220 countries.

[00:15:37] And according to data from the company,

[00:15:39] 1.5 million guests have stayed in an Airbnbs listed property through 2023.

[00:15:45] However, the study has clearly shown that each additional active Airbnbs

[00:15:50] is associated with a 0.16% increase in theft,

[00:15:54] a 0.06% increase in violent offences,

[00:15:57] a 0.04% increase in burglaries,

[00:16:00] and a 0.03% increase in robberies per quarter.

[00:16:05] A new study in the journal Science shows that for some people who believe in conspiracy theories,

[00:16:10] a fact-based conversation with an artificial intelligence chatbot

[00:16:14] can pull them out of the rabbit hole and keep them out for several months.

[00:16:18] While some conspiracy theories are relatively harmless,

[00:16:21] such as those believing in a flat Earth,

[00:16:23] others can cause harm and even death.

[00:16:25] And there are also many major concerns about treating AIs as fonts of all knowledge.

[00:16:31] They're not.

[00:16:32] That's because artificial intelligence makes it really easy to create believable fake content.

[00:16:37] Tim Mendham from Australian Skeptics warns,

[00:16:40] artificial intelligence is only ever as good as the data programmed into it.

[00:16:45] Now there was an experiment made trying to convince conspiracy theories

[00:16:48] out of their beliefs in conspiracies,

[00:16:49] and people who rusted on to conspiracy theories

[00:16:52] and those who were toying with them, etc.

[00:16:53] And so rather than the normal human reaction like skeptics,

[00:16:56] you try and talk someone out of conspiracy theory,

[00:16:58] why do you want to believe this?

[00:17:00] What is the truth of the claims, etc., or untruth of the claims?

[00:17:03] What's the proper explanation for what happened?

[00:17:05] And what they're saying is that humans aren't always very good at doing this

[00:17:07] because you tend to react emotionally.

[00:17:09] So what do you do?

[00:17:10] You attach it to a computer and you get an AI-run computer

[00:17:13] to actually look up the evidence and then present it in a human fashion.

[00:17:16] And apparently they have three sessions in which they can talk back and forth and back and forth.

[00:17:20] And it's been fairly effective, sort of.

[00:17:22] For 20% of people, they don't have their conspiracy theory for a few months afterwards.

[00:17:27] They might go back to their conspiracy theories,

[00:17:29] or they might go on to a different conspiracy theory, which often happens.

[00:17:32] There's a trouble with these AI.

[00:17:33] They're not teaching people how to think and how to be critical thinkers.

[00:17:36] They're teaching them just the facts.

[00:17:37] There are some people who are just pre-positioned to have conspiracy theories.

[00:17:41] It's just their thing.

[00:17:42] And that's not to say that conspiracy theories aren't real.

[00:17:44] There are real conspiracies out there, lots of them.

[00:17:47] That's right.

[00:17:47] There are real conspiracies out there.

[00:17:48] But I mean, we know about a lot of the conspiracy theories that are out there.

[00:17:51] There are some that we don't know about yet, and they're obviously the very effective ones.

[00:17:54] But the resilience of a conspiracy theorist is amazing,

[00:17:57] how they can jump from one to the next to the next to the next.

[00:17:59] And they will deny having believed in the previous one.

[00:18:02] What they're suggesting with the AI is that it's effective because it's not emotional.

[00:18:06] People know it's an AI.

[00:18:07] They know it's a computer in these tests, but they somehow believe it more effectively

[00:18:11] because they say computers don't lie.

[00:18:13] It's garbage in, garbage out.

[00:18:15] Garbage in, garbage out.

[00:18:16] That's the whole problem.

[00:18:17] There's always the human element in the background.

[00:18:19] And if the AI is drawing on biased information, it will spew up biased information in the same

[00:18:24] sort of effective ways and might spew up factual information.

[00:18:27] And that's the trouble.

[00:18:28] And AI can be a force for evil as well as a force for good.

[00:18:32] And AI is not a font of truth.

[00:18:34] And AI is a font of information which it finds very quickly.

[00:18:36] It's often just outright wrong because it often sort of picks up the wrong information,

[00:18:40] not just from misinformation.

[00:18:41] It'll just sort of choose a paragraph from here or a sentence from there and put it in

[00:18:44] as if it were something else.

[00:18:45] That's Tim Mendham from Australian Skeptics.

[00:18:48] And that's the show for now.

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